Table 2.
Anthropometric characteristics, ECG findings, and main clinical data of the study population divided by age class
| Variables | All ages | Age class |
P-values | P-values | |||
|---|---|---|---|---|---|---|---|
| 12–13 | 14–15 | 16–17 | 18–19 | Mixed model analysis | Dunn’s pairwise comparisons | ||
| Only non-significant P-values are reported | |||||||
| N | 24 062 | 11 796 (49%) | 5976 (25%) | 3781 (16%) | 2509 (10%) | ||
| Female, n (%) | 11 715 | 5795 (49) | 2837 (47) | 1945 (51) | 1174 (49) | 0.52 | |
| Height (cm) | 164.4 ± 10.3 | 159.3 ± 8.7 | 167.3 ± 8.8 | 170.4 ± 9.0 | 172.2 ± 1.0 | <0.0001 | |
| Growth rate (cm/years) | 11.7 ± 1.4 | 12.8 ± 0.7 | 11.6 ± 0.7 | 10.3 ± 0.6 | 9.4 ± 0.6 | <0.0001 | |
| Weight (kg) | 56.2 ± 12.6 | 51.3 ± 11.2 | 58.6 ± 11.5 | 62.1 ± 11.5 | 64.5 ± 12.8 | <0.0001 | |
| BMI (kg/m2) | 20.7 ± 5.7 | 20.2 ± 4.1 | 20.9 ± 6.1 | 21.4 ± 6.0 | 21.9 ± 9.3 | <0.0001 | |
| Thinness (%, 95 % CI) | 7.5 (7.1–7.9) | 6.2 (5.7–6.6)* | 6.7 (6.0–7.4)* | 9.9 (9.0–11.0) | 12.1 (10.8–13.5) | <0.0001 | 0.70* |
| I degree | 5.9 (5.6–6.2) | 4.9 (4.5–5.3)* | 5.6 (5.0–6.2)* | 7.0 (6.2–7.9) | 9.3 (8.2–10.6) | <0.0001 | 0.25* |
| II degree | 1.2 (1.0–1.3) | 0.8 (0.7–1.0)* | 0.7 (0.5–1.0)* | 2.1 (1.7–2.7)† | 1.8 (1.3–2.5)† | <0.0001 | 0.99* |
| 0.68† | |||||||
| III degree | 0.5 (0.4–0.6) | 0.3 (0.2–0.4)* | 0.3 (0.2–0.5)* | 0.7 (0.5–1.1)† | 0.9 (0.6–1.4)† | <0.0001 | 0.99* |
| 0.67† | |||||||
| Obesity | 20.9 (20.4–21.5) | 27.1 (26.2–27.9) | 17.6 (16.6–18.7) | 13.5 (12.4–14.7)* | 11.8 (10.5–13.1)* | <0.0001 | 0.30* |
| I degree | 17.3 (16.8–17.9) | 22.2 (21.4–23.0) | 14.4 (13.5–15.4) | 11.9 (10.8–13.0)* | 10.0 (8.8–11.2)* | <0.0001 | 0.17* |
| II degree | 3.6 (3.3–3.8) | 4.8 (4.4–5.2) | 3.2 (2.7–3.7) | 1.7 (1.3–2.1)* | 1.8 (1.3–2.4)* | <0.0001 | 0.99* |
| SBP (mmHg) | 119 ± 15 | 117 ± 14 | 121 ± 15 | 122 ± 15* | 122 ± 15* | <0.0001 | 0.99* |
| DBP (mmHg) | 69.8 ± 11.4 | 69.6 ± 11.7 | 70.4 ± 11.4* | 69.5 ± 10.7† | 70.2 ± 10.8*,† | <0.0001 | 0.27* |
| 0.22† | |||||||
| ECG | |||||||
| Heart rate (bpm) | 80.6 ± 16.1 | 83.6 ± 15.8 | 79.6 ± 16.0 | 76.4 ± 15.6 | 74.3 ± 15.1 | <0.0001 | |
| PR interval (ms) | 136 ± 18 | 133 ± 16 | 137 ± 21 | 138 ± 19* | 140 ± 18* | <0.0001 | 0.08* |
| QRS (ms) | 87 ± 8 | 85 ± 7 | 86 ± 9 | 91 ± 9 | 90 ± 8 | 0.09 | |
| QTc (ms) | 413 ± 61 | 417 ± 32 | 412 ± 108 | 408 ± 29 | 404 ± 28 | <0.0001 | |
| Physical activity (%, 95% CI) | 69.7 (69.1–70.3) | 73.1 (72.4–74.0) | 70.2 (69.0–71.3) | 66.4 (64.9–67.9) | 57.6 (55.6–59.5) | <0.0001 | |
| Smoke (%, 95% CI) | 10.3 (9.9–10.7) | 1.9 (1.7–2.1) | 8.1 (7.4–8.8) | 22.8 (21.4–24.2) | 35.9 (34.0–37.8) | <0.0001 | |
Age class was significant in all variables (except for sex, P = 0.52) as a result of analyses performed using generalized linear mixed models with age class as the independent variable and school as random intercept. All post hoc multiple comparisons performed with the Dunn’s test were significant at the required level of P = 0.05 after Bonferroni’s adjustment, except for the * and † marked pairwise P-values reported in the last column. P-values of significant pairwise comparisons were not reported.
BMI, body mass index; CI, confidence interval; DBP, diastolic blood pressure; QTc, heart rate-adjusted QT interval; SBP, systolic blood pressure.